A “smarter,” lighter 2014 Corvette

Heat-activated, shape memory wire saves weight

The Chevrolet Corvette has been a study in weight-saving technologies since its debut with a fiberglass body in 1953. The campaign for innovation has evolved to an aluminum chassis for the 2014 model.

A lighter Corvette is a quicker Corvette and that aluminum frame weighs 99 pounds less than its predecessor. And now, General Motors is moving into a new frontier of weight consciousness with its development of “smart” materials.

The redesigned seventh-generation ’Vette will be the first vehicle to use a lightweight “shape memory” alloy wire. The wire will be used in place of a heavier motorized actuator to open and close the hatch vent, which releases air from the trunk. The vent allows the trunk lid to close more easily than on the previous models.

Shape memory alloys are typically made of copper-aluminum-nickel or nickel-titanium. They are so-called smart materials because they can change their shape, strength or stiffness when activated by heat, stress, a magnetic field or electrical voltage. Shape memory alloys “remember” their original shape and return to it when de-activated.

In the new Corvette, a shape memory alloy wire uses heat from an electrical current, such as for the trunk lights. When activated, the wire contracts and moves a lever arm to open the vent, allowing the trunk lid to close. When the trunk lid is closed, the electrical current switches off, which allows the wire to cool and return to its normal shape. That closes the vent to maintain cabin temperature.

These smart materials also remove unwanted mass, which can help improve vehicle performance and fuel economy. The wire actuator used on the new Corvette is approximately 1.1 pounds lighter than a motorized system.

With about 200 motorized movable parts on the typical vehicle that could be replaced with lightweight “smart” materials, GM is looking at significant cost and mass savings.

“The shape memory alloy used on the new Corvette represents nearly five years of research and development work on smart materials for which GM has earned 247 patents,” Paul Alexander, GM smart materials and structures researcher, said in a statement. “And it is just the beginning. We have many more smart material applications in the pipeline that will bring even more improvements to our vehicles going forward.”